Clean audio - how to get it

After the joy of just being able to make my own radio waves began to subside, I followed a path familiar to most low power radio broadcasters.
First, we try to get more range. Next we look for sources of content to make our stations interesting to listen to. Then, we start trying to improve the sound quality of our content.
Most of us begin by trying to eliminate that annoying "hummmmm" we start to hear under our content. After that, we try to up the dynamic range and then, make it louder.
Below are a few of the links I've found to be especially useful in both beating our common enemy - HUM, and in moving audio through the chain in the best way possible.

Remember, you can fool your eyes with an animated cartoon offering 30 samples per second but it takes 44,000 samples per second to fool your ears. Time spent improving your audio quality is definitely time well spent!